In high-temperature applications such as retort applications, the sterilization chamber can reach and maintain temperatures in excess of 250° F. for a sufficient period of time to ensure that any potentially harmful organisms that may have entered the product are killed. At such high-temperatures, chemical bonding between polymeric surfaces may occur between the closure and the container. Strong bonding, of course, is desirable for creating a robust seal, but can be potentially problematic for a user removing the closure from the container.
In retort applications, traditional closure designs include a three piece system consisting of a contoured metal disc, a donut-shaped plastisol liner and a threaded ring. The closure is used with a container to form a package. In this three piece design, the soft plastisol liner and an exterior surface of the container do not chemically bond to each other. Because there is no chemical bonding between the plastisol liner and the container, the metal disc and the plastisol liner are easily lifted and separated from the container during removal of the closure from the container. This traditional closure design, however, is not as desirable from a cost perspective. It also not desirable from an environmental perspective of the difficulty in recycling.
It would desirable to provide a closure for a package in high-temperature applications that addresses the above-noted disadvantages.